1. Field of the Invention
The invention relates to an optical device and particularly relates to a light source module.
2. Description of Related Art
Nowadays, a light source module which utilizes multiple point light sources to form a plane light source is extensively applied in various types of display devices. The light source module including a light emitting diode is applicable to many types of products, ranging from small-sized portable electronic products, such as mobile phones, cameras, MP3, to middle-sized or large-sized products, such as digital photo frames, personal monitors, TV screens for vehicles, LCD TVs, etc.
The most important features of the light source module are uniformity and brightness. In order to achieve favorable uniformity, the approach in current technology respectively diffuses the light beams emitted by the point light sources. Generally, the light beam from the point light source is diffused by a lens structure. However, the light beam diffused by the lens structure usually has a large diffusion angle, and human eyes cannot completely receive light with overly large diffusion angles; as a result, the brightness received by human eyes is reduced. Therefore, the approach in current technology tends to dispose a diffusion plate before the lens structure to guide the light beams with overly large diffusion angles, such that human eyes can effectively receive the light beams emitted by the point light sources. However, after being guided by the diffusion plate, many of the light beams will be scattered by the scattering particles in the diffusion plate, and the result of a part of the light beams cannot be transmitted toward a viewing direction of human eyes. Consequently, the light source module has the problem of low efficiency of light utilization.
Related technology is given below for reference. U.S. Pat. No. 7,866,844, U.S. Pat. No. 7,572,036, and US patent application publication No. 20090052192, disclose light sources and lenses. U.S. Pat. No. 6,598,998 discloses a light source device having an LED chip and a lens configured in a light guide. US patent application publication No. 20020015297 discloses a light emitting unit having a cathode tube and an optical wave guide. Taiwan patent No. M319426 discloses a backlight module having a light source, a light guide plate, and a reflective sheet. Japanese patent No. 2000-214460 discloses a backlight module having a light guide body and a reflective sheet. U.S. Pat. No. 7,470,042 and U.S. Pat. No. 7,399,108 disclose illumination light sources having light emitting elements and reflective elements.